A case of extensive bilateral conjunctival habronemiasis in a Connemara gelding

Habronemiasis is a parasitic disease caused by one of three species of nematodes. Adult stages of these worms live in the equine stomach. Larval stages can cause cutaneous forms of habronemiasis, muco-cutaneous forms on the ocular or genital mucosa, as well as pulmonary and erratic forms. Although most prevalent in tropical and subtropical areas, it is distributed worldwide. However, the prevalence of the cutaneous and muco-cutaneous forms is lacking in Western Europe. This report presents a rare form of habronemiasis in the periocular region of a 10 year old Connemara pony in Western France. The pony was presented for evaluation and treatment of his right eye, showing signs of pain for 10 days. Despite previous treatments, no improvement had been observed. The pony had been treated the previous year for periocular habronemiasis with corticosteroid injections. Clinical examination revealed marked blepharospasm with moderate epiphora on the right eye. Yellow granules, reaching 1.5 mm in diameter, could be observed in the medial canthus, close to the lacrimal puncta. The lower eyelid and medial canthus were thickened and numerous hard similar granules could be palpated beneath under the palpebral conjunctiva. Fluorescein dye showed a 2 cm large stromal ulcer facing the previously described granules. Jones test was negative. On the left eye also, the lower eyelid was thickened and subconjonctival granules could be palpated, giving this pony an appearance of bilateral ectropion. A diagnosis of unilateral corneal ulcer and bilateral ectropion likely due to chronic habronemiasis-related sulphur-like granules was made. On the right eye, the visible granules were removed under standing sedation and medical treatment was initiated, allowing corneal healing in two weeks time. Two months later the pony was presented for another corneal ulcer on his right eye. The latter was medically treated and surgical intervention was planned in order to remove the sulphur-like granules on both eyes. Under general anaesthesia, the palpebral and nictitating membrane conjunctiva were incised where the granules could be palpated. They were dissected free. Larger incisions were sutured whereas small ones were left open to heal by secondary intention. Large granules were removed from the right medial canthus through a V-shaped incision that was subsequently closed in two layers. On the right eye, a canaliculosinostomy was then performed. A few granules were fixed in buffered formalin for histopathological analysis. Histopathology revealed a bilateral multifocal eosinophilic granulomatous conjunctivitis, of chronic course and marked intensity, associated with intralesional larval residues, compatible with spiruroid nematode larvae of Habronema sp. Topical antibiotics were given for 10 days, followed by topical steroids for 7 days. After tube removal, 4 weeks postoperatively, the pony showed neither swelling nor discharge on both eyes with no visible ectropion. No further corneal ulceration was detected for at least a year postoperatively. This pony is the first reported case of cutaneo-mucous habronemiasis in France. It is unique by the large number of dense fibrous granules causing ectropion and corneal ulcerations.